This invention generally relates to perfusion type dilatation catheters, such as balloon dilatation catheters used in percutaneous transluminal coronary angioplasty (PTCA).
In classic PTCA procedures, a guiding catheter having a preshaped distal tip is percutaneously introduced into the cardiovascular system of a patient and advanced therein until the preshaped distal tip of the guiding catheter is disposed within the aorta adjacent the ostium of the desired coronary artery. The guiding catheter is twisted or torqued from the proximal end to turn the distal tip of the guiding catheter so that it can be guided into the desired coronary ostium. With over-the-wire systems, a guidewire and a balloon dilatation catheter are introduced into and advanced through the guiding catheter to the distal tip thereof, with the guidewire slidably disposed within an inner lumen of the dilatation catheter. The guidewire is first advanced out the distal tip of the guiding catheter, which is seated in the ostium of the patient's coronary artery, until the distal end of the guidewire crosses the lesion to be dilated. The dilatation catheter is then advanced out of the distal tip of the guiding catheter, over the previously advanced guidewire, until the balloon on the distal extremity of the dilatation catheter is properly positioned across the lesion. Once properly positioned, the balloon is inflated to a predetermined size with radiopaque liquid at relatively high pressures (e.g., generally 4-12 atmospheres) to dilate the stenosed region of the diseased artery. One or more inflations may be necessary to effectively dilate the stenosis. Additional stenoses may be dilatated with the same catheter. When the dilatations are completed, the balloon is deflated to that the dilatation catheter can be removed from the dilated stenosis and blood flow will resume through the dilated artery.
Further details of guiding catheters, dilatation catheters, guidewires, and other devices for angioplasty procedures can be found in U.S. Pat. No. 4,323,071 (Simpson-Robert); U.S. Pat. No. 4,439,185 (Lundquist); U.S. Pat. No. 4,468,224 (Enzmann et al.); U.S. Pat. No. 4,516,972 (Samson); U.S. Pat. No. 4,438,622 (Samson et al.); U.S. Pat. No. 4,554,929 (Samson et al.); U.S. Pat. No. 4,582,185 (Samson); U.S. Pat. No. 4,616,652 (Simpson); U.S. Pat. No. 4,638,805 (Powell); U.S. Pat. No. 4,748,986 (Morrison et al.); and U.S. Pat. No. 4,898,577 (Badger et al.) which are hereby incorporated herein in their entirety by reference thereto.
The assignee of the present application, Advanced Cardiovascular Systems, Inc. introduced an improved dilatation catheter into the market place under the trademark STACK PERFUSION.RTM. Coronary Dilatation Catheter which has a plurality of perfusion ports in the wall of the catheter shaft proximal to the balloon and has one or more perfusion ports in the catheter shaft distal to the balloon. The perfusion ports are in fluid communication with an inner lumen which extends to the distal end of the catheter body. When the balloon on the distal extremity of the dilatation catheter is inflated to dilate a stenosis, oxygenated blood in the artery or the aorta or both, depending upon the location of the dilatation catheter within the coronary anatomy, is forced to pass through the proximal perfusion ports, through the inner lumen of the catheter body and out the distal perfusion ports. This provides oxygenated blood downstream from the inflated balloon to thereby prevent or minimize ischemic conditions in tissue distal to the catheter when the balloon is inflated. As is appreciated by those skilled in the art, tissue distal to a stenosis is frequently already in jeopardy due to ischemic conditions which may exist due to the stenotic region within the artery. As a result, care must be exercised in sizing the perfusion ports and the inner lumen to ensure that there is adequate flow of oxygenated blood to tissue distal to the catheter to eliminate or minimize ischemic conditions. This perfusion catheter has been widely praised and has met with much commercial success.
The assignee of the present invention also markets an improved dilatation catheter under the registered trademark ASC RX.RTM. Coronary Dilatation Catheter which is described and claimed in U.S. Pat. No. 5,040,548 (Yock), U.S. Pat. No. 5,061,273 (Yock) and U.S. Pat. No. 4,748,982 (Horzewski et al.) and which has a short guidewire receiving sleeve or inner lumen extending through a distal portion of the catheter. The sleeve or inner lumen extends proximally a distance of at least about 10 cm from a first guidewire port in the distal end of the catheter to a second guidewire port in the catheter spaced proximally from the inflatable member of the catheter. The second guidewire port is spaced a substantial distance from the proximal end of the catheter and usually not more than about 50 cm from the first guidewire port in the distal end of the catheter. Preferably, a slit is provided in the wall of the catheter body which extends distally from the second guidewire port, preferably to a location proximal to the proximal end of the inflatable balloon. The structure of this catheter allows for the rapid exchange of the catheter without the need for an exchange wire or adding a guidewire extension to the proximal end of the guidewire. The design of this catheter has likewise been widely praised by the medical profession and has been met with much success in the market place because of the advantages of its unique design.
One of the major deficiencies of a perfusion type dilatation catheter has been that the inner lumen, which is adapted to receive the guidewire and to perfuse blood through the interior of the balloon, has such a large diameter that the use of the catheter has been limited to the more proximal stenoses. The present invention minimizes the diameter of the inner perfusion lumen and therefore satisfies this need.